Compressors

Inlet flow distortion causing less than factory rated flow, head or efficiency

Reduced suction piping pressure drop & reduced energy costs

Centrifugal and axial compressor operation and performance are sensitive to velocity and mass distribution at the suction, just as pumps and other rotating equipment. When a compressor's factory performance test is run, the ASME Power Test Code (PTC-10) requires a fully developed uniform velocity and mass flow profile entering the compressor. To accomplish this, PTC-10 states two requirements. First, a minimum straight run of three pipes diameters is required between the last elbow and compressor inlet. Second, a flow equalizer is required at the straight pipe inlet to produce a flat velocity profile and assure an even distribution of gas into the compressor inlet.

In field operations, however, compressors do not have this ideal suction piping configuration. Poor field suction piping includes single, double, and triple elbows immediately upstream of of the compressor, which create a considerable amount of distortion. For example, large multistage axial or centrifugal compressors that are used to supply air for refinery fluid catalytic cracking units, as shown above, have upstream turns in the air suction piping which results in non-uniform mass and flow profiles approaching the splitter in the compressor casing

The CRV® , when placed on the inlet side of an elbow, produces a flat velocity profile and an even distribution of process gas at the elbow exit. This allows the compressor to more closely approach its factory test inlet conditions and performance curves. Typical CRV® locations in compressor feed piping systems are shown above and for multistage externally-cooled compressors below.

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Large Air Compressor In Oil Refinery had Mitered Elbow Close to Compressor Air Intake.